Chlorine-containing polymers stabilized with antimonyl compounds



United States Patent OfiFice 3,347,821 Patented Oct. 17, 1987 Claims priority, application Germany, June 20, 1962, F 37,118, F 37,119 4 Claims. (Cl. 260-4535) This application is a divisional application of applica tion Ser. No. 288,635, as filed June 18, 1963, now US. Patent No. 3,317,576 granted May 2, 1967.

This invention relates to the stabilization of chlorine containing polymers, especially polyvinyl chloride, to stabilizers used therefore and to their production.

It is known that chlorine-containing high molecular Weight compounds such as polymers of vinyl chloride and copolymers of vinyl chloride and vinyl acetate or polymers and copolymers of vinylidene chlorine and chlorination products of higher or polymeric hydrocarbons, such as chlorinated parafiin or chlorinated natural or synthetic rubber must be protected against undesirable changes produced by the action of heat, light or the atmosphere by the addition of stabilizing substances. Polymers of the type described have a hydrocarbon backbone which is characteristic of substantially all olefin, or addition-type polymers. Numerous compounds of many different classes of substances have already been proposed as stabilizers, e.g., inorganic compounds such as oxides, hydroxides, carbonates, phosphates or phosphites of alkali metals and alkaline earth metals as well as heavy metals such as zinic, cadmium or lead. In addition, organic metal compounds, particularly those of tin, and organic compounds such as carboxylic acid hydrazides, phosphoric acid esters and phosphoric acid hydrazides and epoxy compounds are widely used as stabilizers on a technical scale. A stabilizer should as far as possible be suitable for many types of the above mentioned groups of polymers, should at the same time stabilize against heat and light and the action of the atmosphere, should not make it more diflicult to work up the material and should be compatible with additives (e.g., plasticizers). Its physiological properties are also important.

It has now been found that organic antimony compounds which have been obtained by reacting antimony trihalides or antimony trioxide with thioglycollic acid and/ or 1-mercapto-2-hydroxyalkanes in an aqueous medium and which contain in the bound form, per Sb atom, either2 mols of thioglycollic acid or 2 mols of mercaptoalkanol or 1 mol each of thioglycollic acid and mercaptoalkanol are very suitable for use as stabilizers for chlorinecontaining polymers.

The compounds used according to the invention may be prepared, for example, by reacting antimony-(III)- compounds with thioglycollic acid or with 1-mercapto-2- hydroxyalkanes, or with mixtures of these two compounds. When 1-mercapto-Z-hydroxyalkanes are used, the reaction is preferably carried out in an aqueous solution in the neutral or alkaline range, and antimony trioxide may advantageously be used as the antimony compound. Thegeneral reaction with thioglycollic acid, however, may

.also be carried out in an acid medium and/or with the use of antimony trichloride. The reaction components are advantageously used in such quantities thatat least approximately.Zmolecules of the other reaction components are used for each antimony atom. When a mixture of 1-mercapto-2-hydroxy-.

is rendered alkaline by alkanes and thioglycollic acid is used, these two components are preferably used in the molar ratio of 1:1. Although, in principle, the reaction may be carried out in the temperature range of 0 to C., it is preferable to employ a temperature range of 60 to 100 C. Insoluble antimony trioxide, which may in some cases be used as starting material, is gradually converted in a neutral medium to a compound which is soluble at first but which begins to crystallize, after a short time, in the form of a colorless precipitate. This precipitate may be isolated and purified by the usual methods. The process according to the invention is advantageously carried out in an aqueous, alkaline medium. The alkalies may be used, for example, in the form of aqueous solutions of alkali metal hydroxide or carbonates. The reaction products may be recovered by the usual methods, e.g., by cooling and acidification with mineral acids, from the clear, alkaline solutions thereby produced. The constitution of the new compounds is not yet known, but analytical findings show that the compounds contain either 2 mols of mercapto alkanol or 1 mol each of mercapto alkanol and thioglycollic acid per antimony atom.

All these new compounds are colorless compounds which crystallize well and have definite melting points, although sometimes, depending on the starting compounds, they may also be obtained in the form of colorless oils which cannot be distilled. The compounds are stable in storage although they gradually turn brown under the action of direct sunlight.

The new compounds are extremely stable to hydrolytic influences and may, for example, partly be recrystallized from hot water.

Compared with known stabilizers, the compounds used in accordance with the invention have the following advantages, among others: 7

( 1) Their stabilizing effect is excellent.

(2) They are highly compatible with all chlorine containing polymers and with the usual additives (e.g., plasticizers) and can easily be mixed in with them.

(3) They are odorless or almost odorless in themselves and have only slight toxicity in warm-blooded animals, so that there are no objections to their use from a physiological point of view.

(4) The compounds are technically easily accessible and obtainable by simple methods. They may be used either alone or in combination with known stabilizers, and in some cases known stabilizers are considerably improved in their action when present in such combinations.

The stabilizers according to the invention are used in known manner by adding them in quantities of, for exam- -'ple, 0.1 to 5% by weight, preferably 0.3 to 2% by weight, either alone or in mixtures with each other arid/or in mixtures with other stabilizers, to the chlorine-containing high molecular weight compounds. The addition of these stabilizers to polymers or copolymers may be effected, for example, during the polymerization or during the subsequent preparation of the mixture, e.g., on a roller.

Suitable high molecular weight compounds for the process of the invention are, for example, polymers of vinyl chloride or vinylidene chloride, Z-chlorobutadiene or copolymers of these compounds With vinyl acetate or chlorinated rubber or sulphochlorinated polyethylene.

The excellent stabilizing effect of the class of compounds claimed in the invention will be evident from the following examples. The compounds mentioned may be prepared, for example, by the following method:

Compound A.A solution of 18.4 g. of thioglycollic acid and 15.6 g. of mercaptoethanol in about 100 ml. of water is stirred with 2912 g. of Sb O When the slightly exothermic reaction has died down, the reaction mixture means of a solution of 8 g. of NaOH in 30 ml. of water, the temperature of the mixture thereby rising to about 6070 C. The mixture is then heated to about 8090 C. while stirring, a clear solution being formed which is filtered at about 40 to 50 C. to remove traces of impurities and then acidified with halfconcentrated hydrochloric acid at 20 C. A colorless crystalline precipitate is formed which is separated by suction filtration and washed with water until neutral. M.P. after drying on clay; 130 C., after recrystallization from hot water: 138 C. Yield about 40 g.

Analysis.-Calculated for C4HqO3S SB C, 16.6%; H, 2.4%; S, 22.2%; Sb, 42.2%. Found: C, 16.8%; H, 2.5%; S, 22.2%; Sb, 41.9%.

Compound B.-29.2 g. of S b O are stirred into a solution of 31.5 g. of mercaptoethanol in 100 ml. of water. The mixture is then added to a solution of 8 g. of NaOH in ml. of water whereby slight yellow discoloration occurs and the temperature of the mixture rises to about C. The turbid mixture is slowly heated to 7585 C. while stirring, a substantially clear solution thereby being formed. This solution is filtered at room temperature and then treated with about 20 ml. of concentrated hydrochloric acid and at the same time cooled with ice. The colorless crystals thereby precipitated are removed by suction filtration, washed with water until neutral and dried on clay. M.P.: I132-133 C. after recrystallization from isopropanol: 133135 C. Yield about g.

AnalySis. Calculated for C H O S Sb: C, 17.5%; H, 3.3%; S, 23.3%; Sb, 43.3%. Found: C, 17.5%; H, 3.4%; S, 23.2%; Sb, 42.0%. I

Compound C.29.2 g. of Sb O are stirred into a mixture of 16 g. mercaptoehanol, 18.4 g. of mercaptopropanol and 100 ml. of water. This mixture is then treated with a solution of 8 g. of NaOH in 30 ml. of water and heated to 80 to 90 C. The turbid solution is filtered hot and cooled to about 10 C. with a mixture of ice and water. When the solution is acidified with 20 ml. of concentrated hydrochloric acid, an oil separates which is removed and washed with water. The oil crystallizes when stirred into an acetone/water solution. When redissolved from isopropanol, colorless crystals melting at 100 to 103 C. are obtained.

Analysis.-Calculated for C H O S Sb: C, 20.6 H, 3.81%; S, 22.1%; Sb, 42.2%. Found C, 20.6%; H, 3.88%; S, 22.2%; Sb, 42.2%.

Compound D.-29.2 g. of Sb O are stirred into a solution of 18.4 g. of thioglycollic acid and. 18.4 g. of mercaptopropanol in about ml. of water. The mixture is then treated with a solution of 8 g. of NaOH in 30 ml. of water and heated to about 90 C. The turbid solution is filtered hot, cooled to room temperature with a mixture of ice and water and treated with 20 ml. of concentrated hydrochloric acid. The oil thereby formed is separated, washed with water and crystallized by trituration with an acetone/water solution. Melting point of the colorless crystals: 149" C.

The other compounds according to the invention may be prepared in an analogous manner.

The discolorations of the samples given in the examples are indicated by the following numbers:

4 Brownish 3 Yellow, orange 4 Brown, red brown 5 Black 6 Example 1 Portions of 100 parts by Weight of a polyvinyl chloride of K-value 70, prepared by emulsion polymerization, are mixed, in turn, with .1 part by weight of one of the substances (ad) given below by rolling for 10 minutes on mixing rollers heated to 160 C., and the rolled sheets thereby produced are then kept in a heating cupboard heated to 170 C. with circulating hot air. Table I gives the discolorations observed after the given times.

The following are added:

((1) Compound A (b) Compound B (0) Compound C (d) Compound D TABLE 1 IO-Miuute Time Stored in Heating Cupboard (in Rolled minutes) Sample Sheet The discolorations observed are shown in Table 2.

The following are added:

(a) Compound B (b) Compound C The following are added for comparison:

(c) Barium-cadmium-laurate (d) Sulphur-containing organo tin, 9.0% sulphur) (e) Potassium-antimonyl tartrate tin compound (9.8%

60 (7) Antimony-(lII)-triphenolate Colorless h 1 No addltlve Yellowish 2 The following results are obtained:

TABLE 2 IO-Minute Storage Time in Heating Cupboard (in Minutes) Xeno- Sample Rolled test, Sheet 15 i 30 i 45 I 60 90 210 Hours Very adhesive after 5 min.

Example 3 The following are added:

(a) Compound A (b) Compound B The following results are obtained:

Whereas a non-stabilized sample is colored brown even after minutes storage in a heating cupboard, a foil that has been stabilized with the compound according to the invention is still colorless after minutes in the heating cupboard as well as after 100 hours exposure to light in the Xenotest.

We claim:

1. A composition comprising a chlorine-containing polymer having a hydrocarbon backbone stabilized with a stabilizing amount of an organic antimony compound Which is the reaction product, in an aqueous medium, of at least one member selected from the group consisting on antimony trihalide and antimony trioxide with at least TABLE 3 10-Minute Storage in Heating Cupboard (in Minutes) Xeno- Sample Rolled test, Sheet 100 15 30 I I 180 210 Hours Example 4 one member selected from the group consisting of thio- Portions of 60 parts by weight of a polyvinyl chloride of K-value 70 obtained by emulsion polymerization are mixed with 40 parts by weight of dioctylphthalate with the addition of 0.6 part by weight of Compound A by rolling the components for 10 minutes on mixing rollers heated to C. The rolled sheet is then stored in a heating cupboard heated to C.

Whereas a non-stabilized sample is discolored brown after only 15 minutes storage in the heating cupboard and becomes dark brown after 90 minutes, the foil stabilized by the compound according to the invention shows no discoloration eVen after 90 minutes.

Even when the sheet stabilized as described above and rolled for 10 minutes is exposed to a xenon high pressure lamp, there is no discoloration after 100 hours.

Example 5 Portions of 60 parts by weight of a polyvinyl chloride of K-value 70, obtained by emulsion polymerization, and 40 parts by weight of diphenyl-cresyl phosphate together with 0.6 part by weight of Compound B are worked up and tested as described in Example 4.

glycollic acid and 1-mercapto-Z-hydroxy-alkane containing from 2 to 3 carbon atoms, said organic antimony compound containing per antimony atom, one member selected from the group consisting of 2 mols of thioglycollic acid, 2 mols of said l-mercapto-2-hydroxy-alkane and 1 mol each of thioglycollic acid and said l-mercapto- 2-hydroxy-alkane.

2. The composition of claim 1 wherein said selected polymer is polyvinyl chloride.

3. The composition of claim medium is an aqueous alkaline medium.

4. The composition of claim 2 wherein said organic antimony compound contains, per antimony atom, 1 mol of each of thioglycollic acid and l-mercapto-Z-hydroxyethane.

1 wherein said aqueous No references cited.

DONALD E. CZAJA, Primary Examiner. LEON I. BERCOVITZ, Examiner. V. P. HOKE, Assistant Examiner. 

1. A COMPOSITION COMPRISING A CHLORINE-CONTAINING POLYMER HAVING A HYDROCARBON BACKBONE STABILIZED WITH A STABILIZING AMOUNT OF AN ORGANIC ANTIMONY COMPOUND WHICH IS THE REACTION PRODUCT, IN AN AQUEOUS MEDIUM, OF AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING ON ANTIMONY TRIHALIDE AND ANTIMONY TRIOXIDE WITH AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF THIOGLYCOLLIC ACID AND 1-MERCAPTO-2-HYDROXY-ALKANE CONTAINING FROM 2 TO 3 CARBON ATOMS, SAID ORGANIC ANTIMONY COMPOUND CONTAINING PER ANTIMONY ATOM, ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF 2 MOLS OF THIOGLYCOLLIC ACID, 2 MOLS OF SAID 1-MERCAPTO-2-HYDROXY-ALKANE AND 1 MOL EACH OF THIOGLYCOLLIC ACID AND SAID 1-MERCAPTO2-HYDROXY-ALKANE. 